Method for appraising the condition of a semiconductor polishing cloth

Abstract

The present invention provides a method for appraising the condition of a polishing cloth, and a method for manufacturing semiconductor wafers employing the disclosed appraisal method, allowing acceptably low light point defect numbers of semiconductor wafers to be maintained. The disclosed method comprises polishing the semiconductor wafer using a polishing cloth, washing the wafer, and drying the wafer. The size of particles comprising light point defects is chosen, and the number of light point defects on the semiconductor wafer is counted. Typically, the diameter of particles comprising light point defects is set as 0.12 μm or greater. The polishing cloth is exchanged when the number of light point defects counted exceeds a prescribed number.

What is claimed is:  
     
       1. A method for appraising the condition of a polishing cloth used to polish semiconductor wafers, comprising: 
       selecting a diameter of particle defining a light point defect;  
       selecting a number of light point defects;  
       polishing a semiconductor wafer with said polishing cloth;  
       counting a number of light point defects on said semiconductor wafer after said step of polishing; and  
       replacing said polishing cloth if said counted number of light point defects is greater than said selected number of light point defects.  
     
     
       2. The method of  claim 1 , wherein said selected diameter of particle defining a light point defect is greater than about 0.12 μm. 
     
     
       3. The method of  claim 1 , wherein said selected diameter of particle defining a light point defect is greater than a certain diameter, and said certain diameter is about 0.12 μm. 
     
     
       4. The method of  claim 1 , wherein said selected diameter of particle defining a light point defect is greater than a certain diameter, and said certain diameter is about 0.16 μm. 
     
     
       5. A method for appraising the condition of a polishing cloth used to polish semiconductor wafers, comprising: 
       selecting a diameter of particle defining a light point defect;  
       selecting a number of light point defects;  
       polishing a semiconductor wafer with said polishing cloth;  
       washing said semiconductor wafer;  
       drying said semiconductor wafer;  
       counting a number of light point defects on said semiconductor wafer after said step of drying; and  
       replacing said polishing cloth if said counted number of light point defects is greater than said selected number of light point defects.  
     
     
       6. The method of  claim 5 , wherein particles defining light point defects have a diameter greater than about 0.12 μm. 
     
     
       7. The method of  claim 5 , wherein particles defining light point defects have a diameter greater than a certain diameter, and said certain diameter is about 0.12 μm. 
     
     
       8. The method of  claim 5 , wherein particles defining light point defects have a diameter greater than a certain diameter, and said certain diameter is about 0.16 μm. 
     
     
       9. A method for manufacturing semiconductor wafers that are polished using a polishing cloth, comprising: 
       selecting a diameter of particle defining a light point defect;  
       selecting a number of light point defects;  
       polishing a semiconductor wafer with a polishing cloth;  
       washing said semiconductor wafer;  
       drying said semiconductor wafer;  
       counting an actual a number of light point defects on said semiconductor wafer after said step of drying; and  
       replacing said polishing cloth if said actual number of light point defects is greater than said selected number of light point defects before polishing a next semiconductor wafer.  
     
     
       10. The method of  claim 9 , wherein said selected diameter of particle defining a light point defect is greater than about 0.12 μm. 
     
     
       11. The method of  claim 9 , wherein said selected diameter of particle defining a light point defect is greater than a certain diameter, and said certain diameter is about 0.16 μm. 
     
     
       12. The method of  claim 9 , wherein said selected diameter of particle defining a light point defect is greater than a certain diameter, and said certain diameter is about 0.12 μm. 
     
     
       13. A method for appraising the condition of a polishing cloth used to polish semiconductor wafers, comprising: 
       selecting a diameter of particle defining a light point defect;  
       selecting a number of light point defects;  
       polishing a semiconductor wafer with said polishing cloth;  
       counting all light point defects of said selected diameter on said semiconductor wafer after said step of polishing; and  
       replacing said polishing cloth if said counted number of light point defects is greater than said selected number of light point defects.  
     
     
       14. The method of  claim 13 , wherein said selected diameter of particle defining a light point defect is greater than about 0.12 μm. 
     
     
       15. The method of  claim 13 , wherein said selected diameter of particle defining a light point defect is greater than about 0.16 μm. 
     
     
       16. A method for appraising the condition of a polishing cloth used to polish semiconductor wafers, comprising: 
       selecting a diameter of particle defining a light point defect;  
       selecting a number of light point defects;  
       polishing a semiconductor wafer with said polishing cloth;  
       washing said semiconductor wafer;  
       drying said semiconductor wafer;  
       counting all light point defects of said selected diameter on said semiconductor wafer after said step of drying; and  
       replacing said polishing cloth if said counted number of light point defects is greater than said selected number of light point defects.  
     
     
       17. The method of  claim 16 , wherein said selected diameter of a particle defining a light point defect is greater than about 0.12 μm. 
     
     
       18. The method of  claim 16 , wherein said selected diameter of a particle defining a light point defect is greater than about 0.16 μm. 
     
     
       19. A method for manufacturing semiconductor wafers that are polished using a polishing cloth, comprising: 
       selecting a diameter of particle defining a light point defect;  
       selecting a number of light point defects;  
       polishing a semiconductor wafer with a polishing cloth;  
       washing said semiconductor wafer;  
       drying said semiconductor wafer;  
       counting all light point defects of said selected diameter on said semiconductor wafer after said step of drying; and  
       replacing said polishing cloth if said counted number of light point defects is greater than said selected number of light point defects before polishing a next semiconductor wafer.  
     
     
       20. The method of  claim 19 , wherein said selected diameter of a particle defining a light point defect is greater than about 0.12 μm. 
     
     
       21. The method of  claim 19 , wherein said selected diameter of a particle defining a light point defect is greater than about 0.16 μm. 
     
     
       22. A method for appraising the condition of a polishing cloth used to polish semiconductor wafers so as to achieve fewer than a first number of light point defects of at least a first diameter on said wafers, comprising: 
       polishing a semiconductor wafer with said polishing cloth;  
       counting all light point defects of at least said first diameter on said semiconductor wafer after said step of polishing; and  
       replacing said polishing cloth if said counted number of light point defects is greater than said first number of light point defects.  
     
     
       23. The method of  claim 22 , wherein said first diameter is greater than about 0.12 μm. 
     
     
       24. The method of  claim 22 , wherein said first diameter is greater than about 0.16 μm. 
     
     
       25. A method for appraising the condition of a polishing cloth used to polish semiconductor wafers so as to achieve fewer than a first number of light point defects of at least a first diameter on said wafers, comprising: 
       polishing a semiconductor wafer with said polishing cloth;  
       washing said semiconductor wafer;  
       drying said semiconductor wafer;  
       counting all light point defects of at least said first diameter on said semiconductor wafer after said step of drying; and  
       replacing said polishing cloth if said counted number of light point defects is greater than said first number of light point defects.  
     
     
       26. The method of  claim 25 , wherein said first diameter is greater than about 0.12 μm. 
     
     
       27. The method of  claim 25 , wherein said first diameter is greater than about 0.16 μm. 
     
     
       28. A method for manufacturing semiconductor wafers that are polished using a polishing cloth so as to achieve fewer than a first number of light point defects of at least a first diameter on said wafers, comprising: 
       polishing a semiconductor wafer with a polishing cloth;  
       washing said semiconductor wafer;  
       drying said semiconductor wafer;  
       counting all light point defects of at least said first diameter on said semiconductor wafer after said step of drying; and  
       replacing said polishing cloth if said counted number of light point defects is greater than said first number of light point defects before polishing a next semiconductor wafer.  
     
     
       29. The method of  claim 28 , wherein said first diameter is greater than about 0.12 μm. 
     
     
       30. The method of  claim 28 , wherein said first diameter is greater than about 0.16 μm. 
     
     
       31. A method for polishing semiconductor wafers, comprising: 
       a) specifying a minimum light point defect diameter;  
       b) specifying a maximum acceptable number of light point defects having a diameter at least as large as said minimum light point defect diameter;  
       c) after completing steps a and b, polishing a semiconductor wafer with a polishing cloth;  
       d) after completing step c, counting a number of light point defects on said semiconductor wafer having a diameter at least as large as said specified diameter to obtain a counted number of light point defects; and  
       e) replacing said polishing cloth in response to a counted number of light point defects that is greater than said specified maximum acceptable number of light point defects having a diameter at least as large as said specified diameter.